Code improvements

Author: AntoinePrv

.github/workflows/linux.yml

@@ -120,17 +120,17 @@ jobs:
       run: cmake --build _build
     - name: Test
       run: |
-        # Set CPU feature test expectations
-        # Assuming the runner always has AVX (independent of compilation option)
+        # Set CPU feature test expectations, 0 is explicit absence of the feature
         export XSIMD_TEST_CPU_ASSUME_NEON64="0"
-        export XSIMD_TEST_CPU_ASSUME_SSE4_2="1"
-        export XSIMD_TEST_CPU_ASSUME_AVX="1"
-        export XSIMD_TEST_CPU_ASSUME_MANUFACTURER="intel,amd"
         cd _build/test
         if echo '${{ matrix.sys.flags }}' | grep -q 'avx512' ; then
-            export XSIMD_TEST_CPU_ASSUME_AVX512F="1"
+          # Running with emulation, must have AVX512, lower tier are checked by implications in tests
+          export XSIMD_TEST_CPU_ASSUME_AVX512F="1"
           ../../sde-external-9.48.0-2024-11-25-lin/sde64 -tgl -- ./test_xsimd
         else
-            export XSIMD_TEST_CPU_ASSUME_AVX512F=$(grep -q 'avx512f' /proc/cpuinfo && echo "1" || echo "0")
+          export XSIMD_TEST_CPU_ASSUME_SSE4_2=$(grep -q 'sse4_2' /proc/cpuinfo && echo "1" || echo "0")
+          export XSIMD_TEST_CPU_ASSUME_AVX=$(grep -q 'avx' /proc/cpuinfo && echo "1" || echo "0")
+          export XSIMD_TEST_CPU_ASSUME_AVX512F=$(grep -q 'avx512f' /proc/cpuinfo && echo "1" || echo "0")
+          export XSIMD_TEST_CPU_ASSUME_MANUFACTURER="intel,amd"
           ./test_xsimd
         fi

test/test_cpu_features.cpp

@@ -24,10 +24,10 @@ namespace detail
 {
     void check_env_flag(const char* env_var, const char* feature_name, bool actual)
     {
-        const char* val = std::getenv(env_var);
-        if (val)
+        if (const char* val = std::getenv(env_var))
         {
-            // Doctest struggles with string litteras and const char *
+            // Doctest struggles with string literals and const char *
+            // TODO(c++20): use std::format
             auto msg = std::string(env_var) + " = " + val + ", " + feature_name + " = " + (actual ? "true" : "false");
             INFO(msg);
             CHECK_EQ(actual, val[0] == '1');